On the resonance sound generated in a vehicle cabin moving at low speed due to breaking force

Abstract

To improve the comfortability in a vehicle cabin, unwanted noise which is recognized as an allophone generated from automobile wheels was experimentally studied to investigate its generation mechanism and to develop its reduction countermeasures. In this experiment, simultaneous measurements of sound pressure and vibrational acceleration of the wheel surface were performed. Then, frequency analysis, vibrational modal analysis and operational transfer path analysis were performed by using measured data. The results show that this kind of noise started in a low frequency first and then became higher. Furthermore, the high-frequency noise was mainly generated by vibrational acceleration at its center and near the rim when the wheel spoke gets close to the brake caliper. The high-frequency noise is around 250Hz, 750Hz, 1000Hz and 1250Hz, and the wheel spoke easily gets vibration and resonance mainly from around 750Hz and 1000Hz. Vibration at 750Hz occurs on the side of the wheel spoke in the rotation direction, while vibration at 1000Hz occurs at the midpoint of the wheel spoke. The closer to the brake caliper, louder noise was generated at the wheel spoke.